JPH11311116A - Blowby gas reduction structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blowby gas reduction structure that reduces a backflow to the throttle upstream side of a fouling component in blowby gas. SOLUTION: A throttle 20 comprises a throttle body 22 and a throttle valve 24, and an air-flow meter 10 is installed at the upstream side of this throttle valve 24, so as to be projected into an intake air passage 12. The throttle body 22 is formed with a fresh air inlet port 34 for blowby gas reduction at the more upstream side than the throttle valve 24 and at the more downstream side than this air-flow meter 10 respectively, and a partition wall part 38 is formed so as to cover an opening part 36 or its tip part. The partition wall part 38 is formed so as to interrupt a straight line connecting the opening part 36 and the air-flow meter 10, therefore a part of the blowby gas reversed collides with a surface at the side of the opening part 36 and thereby liquefied, while the rest unliquefied is discharged into the intake air passage 12 along an inner wall surface of the throttle body 22 at the side of the throttle valve 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow-by gas reducing structure in which blow-by gas generated in an internal combustion engine is sent to an intake device and recombusted.

[0002]

2. Description of the Related Art An ordinary vehicle includes an internal combustion engine (engine).
A blow-by gas reduction device (PC) that guides the engine again through the intake manifold and reburns it without releasing gas that blows through the gap between the cylinder and piston into the atmosphere
V; Positive Crankcase Ventilation). Reburning the blow-by gas makes it possible to reduce HC.

The above-described blow-by gas returning device includes a closed system that discharges blow-by gas to a surge tank and takes in air from upstream of a throttle;
It is broadly divided into a shield system that uses the internal pressure of the crankcase to return blow-by gas to the upstream side of the throttle without taking in new air. Examples of the shield system include a "blow-by gas suction unit" disclosed in Japanese Utility Model Laid-Open No. 58-33714 and Japanese Utility Model Laid-Open No. 58-510.
A "blow-by gas reduction device" disclosed in Japanese Patent Application Publication No. 08-08,083 is known. Each device in these shield systems:
It has the advantages of a relatively simple structure and no maintenance.However, if the air cannot be ventilated by fresh air and the separation of the oil is not sufficient, moisture and oil will not flow into the air cleaner element upstream of the intake air. It has the disadvantage that it is easily adhered.

On the other hand, the closed system takes in fresh air from the upstream side of the throttle and ventilates the inside of the crankcase, so that the blow-by gas can be efficiently reduced and the surge system located downstream of the throttle in the surge tank. Blow-by gas is taken in, it is difficult for the taken-in blow-by gas to flow backward along the flow of intake air upstream of the throttle (hereinafter, the flow of intake air flowing from upstream to downstream via the throttle is referred to as "main flow"). It has a structure.

[0005]

As described above, in the blow-by gas reducing apparatus employing the closed system, there is a possibility that the blow-by gas taken into the crankcase flows directly backflow along the main flow upstream of the throttle. Although small, the blow-by gas that has flowed back through the fresh air intake provided upstream of the throttle cannot be completely eliminated, and there is a possibility that the blow-by gas may contaminate an air flow meter or the like arranged upstream of the throttle. For example, when the opening of the throttle valve increases,
The negative pressure on the surge tank side decreases, and the pressure difference between the downstream and upstream of the throttle decreases. Moreover, as the throttle opening increases, the engine speed increases, and the amount of blow-by gas generated increases. For this reason, the amount of blow-by gas generated in the crankcase becomes larger than the amount of blow-by gas taken into the surge tank, and the blow-by gas may flow backward from the fresh air intake port to the throttle upstream side.

[0006] In particular, recently, the size of the intake device has been reduced, and an air flow meter may be installed upstream of the throttle and in the vicinity thereof, so that the oil, fuel, moisture, etc., in the blow-by gas flowing backward. If such a dirt component adheres to the air flow meter, it becomes impossible to accurately measure the flow rate of the intake air, which is not preferable. The present invention has been created in view of the above points, and its purpose is to
It is an object of the present invention to provide a blow-by gas reducing structure for reducing a back flow of a dirt component in a blow-by gas to an upstream side of a throttle.

[0007]

In order to solve the above-mentioned problems, in the blow-by gas reducing structure of the present invention, an air intake for reducing the blow-by gas is formed on the inner wall surface of the intake passage upstream of the throttle valve. It has a partition that is shaped to cover the air intake and that opens to the downstream side of the intake air. Normally, fresh intake air is introduced from the air intake, but even if blow-by gas flows back into this air intake when the opening of the throttle bubble becomes large, etc. A part of the dirt component in the gas is liquefied by the backflow blow-by gas colliding with the partition wall, so the amount of dirt component in the blow-by gas discharged into the intake passage from the opening formed on the downstream side is reduced. can do.

[0008] Further, it is preferable that the above-mentioned air intake be provided on the side of the throttle piece that moves upstream of the intake air. Generally, the flow velocity of the intake air is maximum at a small portion of the gap between the valve piece of the throttle valve and the inner wall surface of the intake passage. Therefore, forming the air intake port on the side of the valve that moves upstream of the throttle valve means that the air intake port is formed near the portion where the flow rate of the intake air is the fastest, and the air intake port is liquefied by collision with the partition wall. The blow-by gas discharged into the intake passage without being liquefied or liquefied can be efficiently sucked to the downstream side of the throttle along the main flow.

It is preferable that the above-described air intake is provided at a position where the cross-sectional area of the intake passage is reduced along the flow of the intake air. When the cross-sectional area of the intake passage decreases,
Since the flow velocity of the intake air increases by that amount, the liquefied components colliding with the partition wall and the blow-by gas discharged into the intake passage without being liquefied are efficiently guided to the downstream side of the throttle along the main flow. Can be.

It is preferable that the above-mentioned partition has a surface on the air intake side substantially parallel to the inner wall surface of the intake passage. By forming such a partition, the blow-by gas which is released into the intake passage without being liquefied by colliding with the partition can be flowed along the inner wall surface of the intake passage, so that the blow-by gas is released into the intake passage. The liquefaction of the dirt component in the blow-by gas is promoted, and the dirt component amount in the blow-by gas flowing backward in the intake passage can be further reduced.

It is preferable that the above-mentioned partition has a curved surface on the side of the air inlet. By forming the partition wall portion in a curved shape, the blow-by gas that is released into the intake passage without being liquefied by colliding with the partition wall portion can be more positively applied to the inner wall surface of the intake passage. Liquefaction of components is further promoted, and contaminant components in blow-by gas flowing backward in the intake passage can be further reduced.

It is preferable that the above-mentioned partition wall form a separation part along the main flow at substantially the center of the surface on the air intake side. Usually, since the intake passage is often formed using a cylindrical member, the distance between the partition and the inner wall surface of the intake passage is greatest at the center of the partition. Therefore, a separation portion is formed in the central portion so that the blow-by gas is discharged into the intake passage from the vicinity of the end other than the central portion, so that the discharged blow-by gas collides with the inner wall surface of the intake passage. This facilitates the liquefaction of the dirt component in the blow-by gas.

Preferably, the above-mentioned partition is formed of a member separate from the inner wall surface of the intake passage. By forming the partition wall with a separate member, the respective shapes of the partition wall and the inner wall surface of the intake passage are simplified, so that the manufacture becomes easy especially when each is molded. When a flow measuring unit for measuring the flow rate of the intake air is mounted upstream of the throttle valve, it is preferable that the position where the air intake is formed does not overlap with the flow measuring unit along the main flow. If the flow measurement part protrudes into the intake passage, the downstream air flow along the main flow will be disturbed, so set the air intake so that it does not overlap with the flow measurement part and avoid the part where this air flow is disturbed In this way, the components liquefied in and around the partition wall due to the backflow from the air intake section and the blow-by gas discharged into the intake passage without being liquefied are efficiently sucked into the downstream side of the throttle along the main flow. Can be.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a blow-by gas returning structure according to an embodiment of the present invention, a partition wall portion is provided so as to cover a fresh air intake for returning a blow-by bus, and a part thereof is located downstream of intake air. It is characterized in that blow-by gas flowing backward from the crankcase of the engine is discharged from the opening formed on the side toward the intake passage wall surface. Hereinafter, regarding an intake device for an engine according to an embodiment to which the present invention is applied,
This will be specifically described with reference to the drawings.

The intake device of this embodiment includes a throttle 20 in which an air flow meter 10 is integrally mounted. FIG. 1 is a diagram showing a detailed structure of a throttle 20 included in an intake device for an engine according to an embodiment, and shows a state where an air flow meter 10 is mounted and integrated. Further, FIG.
It is a line sectional view.

As shown in FIGS. 1 and 2, the throttle 20 includes a throttle body 22 and a throttle valve 24.
The air flow meter 10 is attached to a part of the throttle body 22 and upstream of the intake air from a position where the throttle valve 24 is attached so as to protrude into the intake passage 12. The throttle body 22 is a stepped cylindrical member, and a space surrounded by an inner wall surface of the throttle body 22 becomes the intake passage 12. Therefore, throttle body 2
The inner wall surface 2 is also the inner wall surface of the intake passage 12. The throttle body 22 includes an upstream body portion 26 having a large inner diameter arranged on the upstream side along the mainstream flow, and a downstream body portion 28 having a small inner diameter arranged on the downstream side. The upstream body part 26 has an airflow meter 1
A mounting hole for mounting the air flow meter 10 is formed by inserting the air flow meter 10 into the mounting hole from the outer peripheral side of the upstream body portion 26 and fixing the mounting hole.
0 is performed.

The air flow meter 10 employs various types. For example, in this embodiment, a hot wire type is used. The hot wire air flow meter 10 utilizes the fact that a heated resistance wire arranged in a flow path of the intake air is cooled by the intake air, and takes out a temperature change of the resistance wire as a voltage change, thereby obtaining an intake air flow rate. Is detected. In order to maintain high detection accuracy, it is necessary to minimize the attachment of dirt components such as oil, fuel, and moisture in the blow-by gas flowing backward along the main flow.

A throttle valve 24 comprising a shaft 30 and a circular valve piece 32 is attached to the downstream body portion 28 of the throttle body 22 so as to be rotatable about the shaft 30. This shaft 30
Is the throttle valve 2 outside the throttle body 22
4 is connected to a lever (not shown) for arbitrarily setting the opening of the throttle valve 24, and the opening of the throttle valve 24 is changed by changing the rotation angle of this lever according to the amount of depression of the accelerator pedal. Has become. The throttle body 22 is attached so that the above-described insertion direction of the air flow meter 10 and the direction of the shaft 30 match. In other words, by matching the mounting direction of the air flow meter 10 with the direction of the shaft 30,
The increase of the suction resistance and the disturbance of the flow of the suction air due to the mounting of the air flow meter 10 are reduced as much as possible.

When the foot is released from the accelerator pedal,
The throttle valve 24 is fully closed, and a predetermined amount of intake air supplied to the engine through an idle speed control valve (not shown) and the leaked air when the throttle valve 24 is fully closed. An idling state where the engine speed is constant is maintained. When the accelerator pedal is depressed, the throttle valve 24 is opened, and the throttle valve 24 is opened via a gap formed between the throttle valve 24 and the inner wall surface of the downstream body portion 28 of the throttle body 22. An amount of intake air proportional to the degree is taken into each cylinder of the engine.

Further, a fresh air intake port 34 for blow-by gas reduction is formed in the downstream body portion 28 of the throttle body 22 upstream of the throttle valve 22, and serves as an air intake port which is a tip portion thereof. The opening 36 communicates with the intake passage 12. Further, the partition wall portion 38 is formed so as to cover the opening portion 36 by the downstream side body portion 2.
8 is formed integrally with the inner wall surface.

The opening 36 of the fresh air intake port 34 described above.
Is formed on the side of the valve piece 32 that moves upstream when the throttle valve 24 rotates. The partition 38 is formed at a position that blocks a space connecting the opening 36 and the air flow meter 10. The throttle 20 of the present embodiment has such a structure, and its operation will be described below. When the opening of the throttle valve 24 is small, the negative pressure on the downstream side of the throttle valve 24 increases, and in this state, the amount of blow-by gas generated is small because the engine speed is low. Therefore, most of the generated blow-by gas is taken into a surge tank (not shown) on the downstream side of the throttle valve 24, and the opening 36 of the fresh air intake port 34 formed on the upstream side of the throttle valve 24. From there, fresh air containing no impurities is taken into the engine crankcase.

However, when the opening of the throttle valve 24 increases, the negative pressure on the downstream side of the throttle valve 24 decreases, the engine speed increases, and the amount of generated blow-by gas increases. Cannot be taken into the surge tank. In addition, since a large amount of blow-by gas increases the pressure in the engine's clan case, a part of the generated blow-by gas flows back through the fresh air intake port 34 and passes through the opening 36 into the throttle body 22. To enter.

FIG. 3 shows the opening 36 of the fresh air intake port 34.
It is a figure which shows the surrounding detailed structure. As described above, since the partition 38 is formed so as to cover the opening 36,
The blow-by bus that flows backward through the fresh air intake port 34
From the opening 36 to the intake passage 1 inside the throttle body 22
2, but once collides with the partition wall 38. For this reason, some of the dirt components in the blow-by gas that collided with the partition wall portion 38 are liquefied. Further, the blow-by gas that has flowed backward is discharged to the intake passage 12 side through an opening 40 formed on the downstream side of the partition wall portion 38, and the surface of the partition wall portion 38 on the opening side 36 is separated from the downstream body portion 28. The inner wall surface of the downstream body portion 28 is formed substantially parallel to the inner wall surface of the downstream body portion 28 by making the area of the opening 40 small so that the end portion of the partition wall portion 38 and the inner wall surface of the downstream body portion 28 approach each other. It is designed to be released along the wall. Therefore, since the blow-by gas discharged into the intake passage 12 flows along the inner wall surface of the downstream body portion 28, the liquefaction of the dirt component in the blow-by gas is promoted.

As described above, when the dirt component in the blow-by gas is liquefied by colliding with the partition wall portion 38 or the inner wall surface of the downstream side body portion 28, the liquefied component is removed from the inside of the downstream side body portion 28. It is sucked downstream along the wall.
In addition, although there is a part of the dirt component in the blow-by gas discharged into the intake passage 12 without being liquefied, the amount is small since the liquefied residue is present at the end of the partition wall 38. Since the opening 40 faces the downstream side, it is discharged to the downstream, merges with the main flow, is sucked to the engine side, and floats in the intake passage 12 and adheres little to the air flow meter 10.

As described above, the throttle 10 according to the present embodiment is
In this embodiment, a partition 38 is formed so as to cover the opening 36 of the fresh air intake port 34 provided for taking in fresh air for blow-by gas reduction, and the blow-by gas flows back through the fresh air intake port 34. In this case, since a portion of the dirt component in the gas collides with the partition 38 and is liquefied, the amount of dirt component in the blow-by gas discharged to the intake passage 12 in the throttle body 22 can be reduced. it can. The partition 38 is formed at a position that blocks a straight line connecting the opening 36 of the fresh air intake port 34 and the air flow meter 10, and the opening 40 from which the blow-by gas is discharged is located downstream of the intake air. Because it is formed for
The dirt component in the blow-by gas flowing toward the air flow meter 10 can be further reduced. Therefore, it is possible to effectively prevent the contamination component in the blow-by gas from adhering to the air flow meter 10. In particular, the partition 3
The blow-by gas discharged into the intake passage 12 from the opening 40 of the nozzle 8 along the inner wall surface of the throttle body 22 can further promote the liquefaction of the dirt component in the blow-by gas, and the upstream side of the intake passage 12 The contaminant component in the blow-by gas flowing back to the blower can be reduced.

Considering that when the throttle valve 22 is opened, the flow rate of the intake air in the gap formed between the valve piece 32 and the inner wall surface of the throttle body 22 becomes the fastest, the fresh air is taken into consideration. It is preferable that the inlet port 34 and the partition 38 are formed on the side of the valve piece 32 that moves upstream when the throttle valve 22 is opened. Thereby, the component liquefied in the partition part 38 and its vicinity, or the blow-by gas discharged into the intake passage 12 from the opening part 40 of the partition part 38 without being liquefied can be efficiently sucked along the main flow. Similarly, by forming the fresh air intake port 34 and the partition wall portion 38 in the downstream side body portion 28 where the flow of the intake air is increased due to the reduction in the cross-sectional area, the liquefied components and the intake passage without being liquefied are formed. The blow-by gas discharged to the nozzle 12 can be efficiently sucked along the main flow.

The fresh air intake port 34 and the partition 3
8 is formed at a position where it does not become a shadow of the air flow meter 10 (a position where it does not overlap behind the air flow meter 10 along the flow of the intake air), so that the turbulence of the flow of the intake air near the partition 38 is small. Therefore, the liquefied components and the blow-by gas discharged to the intake passage 12 without being liquefied can be more efficiently sucked along the main flow.

FIG. 4 is a view showing a modification of the partition.
The partition 38A shown in FIG. 4 has a curved surface on the side of the opening 36 with which the blow-by gas flowing backward collides. By using such a partition portion 38A, the discharge direction of blow-by gas discharged from the opening portion 40 into the intake passage 12 without being liquefied can be positively directed to the inner wall surface of the throttle body 22. Liquefaction of the dirt component in the gas can be promoted. Also,
When a part of the contaminant component in the blow-by gas that has flowed back has liquefied, the liquefied component can be accumulated on the surface formed into a curved surface, so that the liquefied component discharged into the intake passage 12 is reduced. There is also an effect.

FIG. 5 is a view showing another modification of the partition wall. FIG. 6 is a sectional view taken along the line AA shown in FIG.
The partition part 38B shown in FIGS. 5 and 6 has a separator 42 as a separating part in the center along the main flow, and the flow of the blow-by gas flowing backward is divided by the separator 42. Therefore, the partition 38
The flow of the dirt component in the blow-by gas that has not been liquefied due to the collision with B is released into the intake passage 12 after being separated into two groups by the separator 42. by the way,
Since the inner wall surface of the throttle body 22 is formed in a circular cross section, the distance between the partition wall 38B and the inner wall surface of the throttle body 22 indicates that the central portion where the separator 42 is formed is the farthest. Therefore, the separator 42 is formed in the partition wall 38B, and the intake passage 12
By dividing the flow of the blow-by gas discharged into the inside into two groups excluding the central portion, the blow-by gas is discharged to a position near the inner wall surface of the throttle body 22, so that the discharged blow-by gas Is more likely to hit the inner wall surface of the throttle body 22, and the liquefaction of the dirt component in the blow-by gas is further promoted.

Although the above-mentioned various partition portions 38 and the like are integrally formed with the throttle body 22, they may be formed by separate members. FIG.
FIG. 9 is a view showing another modification of the partition wall. The partition 38C shown in FIG. 7 is formed as a lid of a tubular member 44 which is a separate member from the fresh air intake port 34C integrally formed with the throttle body 22. The tubular member 44 has a simple shape that can be easily formed of a metal material or a resin material. The throttle body 22C also has no complicated protruding portion such as the partition wall portion 38C, and therefore has a simple shape. Particularly, when these parts are manufactured by molding, the manufacture becomes easy.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, in the above-described embodiment, the case in which the air flow meter 10 is integrated with the throttle body 22 has been described. However, the throttle body and the air flow meter are formed as separate components, and these components are assembled when assembled to the engine. You may make it assemble.

[Brief description of the drawings]

FIG. 1 is a diagram showing a detailed structure of a throttle included in an intake device for an engine according to an embodiment.

FIG. 2 is a sectional view taken along line II-II shown in FIG.

FIG. 3 is a diagram showing a detailed structure around an opening of a fresh air intake port.

FIG. 4 is a view showing a modification of a partition.

FIG. 5 is a view showing another modification of the partition.

FIG. 6 is a sectional view taken along the line AA shown in FIG. 5;

FIG. 7 is a view showing another modified example of the partition.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Air flow meter 20 Throttle 22 Throttle body 24 Throttle valve 26 Upstream body part 28 Downstream body part 30 Shaft 32 Valve piece 34 New air intake port 36, 40 Opening part 38 Partition part

Claims (14)

[Claims] An air intake port for blow-by gas reduction is provided on an inner wall surface of an intake passage upstream of a throttle valve, and a partition wall portion having a shape covering the air intake port and opening to a downstream side of the intake air is provided. A blow-by gas reduction structure comprising: 2. The blow-by gas reduction structure according to claim 1, wherein the air intake port is provided on a side of a valve piece of the throttle valve that moves upstream of the intake air. 3. The air intake port according to claim 1, wherein the air intake port is provided at a position upstream of the throttle valve and at a position where the cross-sectional area of the intake passage decreases along the flow of the intake air. Blow-by gas reduction structure. 4. The partition according to claim 1, wherein a surface of the partition on the side of the air intake is formed substantially parallel to an inner wall surface of the intake passage. A blow-by gas flowing backward toward the intake passage along the inner wall surface of the intake passage. 5. The blow-by according to any one of claims 1 to 3, wherein the partition wall has a curved surface on the side of the air intake, and flows backward from the air intake toward the partition. A blow-by gas reducing structure for discharging gas toward the inner wall surface of the intake passage. 6. The air conditioner according to claim 4, wherein the partition has a separating portion formed substantially in the center of the surface on the air intake side in a direction along the flow of the intake air. Blow-by gas reduction structure. 7. The blow-by gas reducing structure according to claim 1, wherein the partition wall is formed by a member separate from the inner wall surface of the intake passage. 8. The air intake according to claim 1, wherein a flow rate measurement unit for measuring a flow rate of the intake air protrudes from a predetermined position on an inner wall surface of the intake passage upstream of the throttle valve. A blow-by gas reducing structure, characterized in that a mouth is formed at a position downstream of the mounting position of the flow measuring unit and not overlapping with the mounting position of the flow measuring unit along the flow of the intake air. 9. A hollow cylindrical member is provided with a flow measuring section for measuring a flow rate of intake air, an air intake for blow-by gas reduction, and a throttle valve in order from the upstream side along the flow of intake air. A blow-by gas reduction structure, characterized in that a partition wall is provided on a line connecting the flow rate measuring section and the air intake port, the partition wall portion being shaped to cover the air intake port and opened to the downstream side of the intake air. 10. The intake member according to claim 9, wherein the tubular member has a stepped structure in which a sectional area of an intake passage decreases along a flow of the intake air. A position that does not overlap with the mounting position of the flow rate measuring unit along the flow of the flow rate, is a valve piece side of the throttle valve that moves upstream of the intake air, and is an inner wall surface of the tubular member. A blow-by gas reducing structure, wherein a cross-sectional area of the intake passage is reduced. 11. The partition according to claim 9, wherein the partition has a surface on the air intake side substantially parallel to an inner wall surface of the tubular member. A blow-by gas reducing structure, wherein blow-by gas flowing backward is discharged along the inner wall surface of the tubular member. 12. The partition wall according to claim 9, wherein the partition wall has a curved surface on the side of the air intake, and the blow-by gas flowing backward from the air intake toward the partition. A blow-by gas reducing structure for discharging toward the inner wall surface of a tubular member. 13. The air conditioner according to claim 11, wherein the partition has a separating portion formed substantially at a center of a surface on the air intake side in a direction along the flow of the intake air. Blow-by gas reduction structure. 14. The blow-by gas reducing structure according to claim 9, wherein the partition is formed by a member different from the tubular member.